Stores analogue to @DataJpaTest

[joshuajaharwood]

Is your feature request related to a problem? Please describe.
Injecting a Store in to a unit test class annotated with @DataJpaTest is unsupported, and throws an exception.

Describe the solution you'd like
A Spring Content analogue to @DataJpaTest for unit testing purposes, such as @StoresJpaTest

Describe alternatives you've considered
I'm not aware of any real alternatives, except for running the same Spring Content code as a real class on a real database, but doing so without an @jpatest annotation prevents transactions from being rolled back.

Additional context
As discussed on gitter.